1. Field of the Invention
The present invention relates to an optical lens system, an optical module having the optical lens, a backlight assembly having the optical lens, and a display device having the optical lens. More particularly, the present invention relates to an optical lens system capable of improving optical characteristics, an optical module having the optical lens, a backlight assembly having the optical lens, and a display device having the optical lens.
2. Description of the Related Art
Generally, a display device is a device for visual presentation of images acquired, stored, or transmitted in various forms. Common display device types are analog electronic displays, such as a cathode ray tube (CRT) display, and digital electronic displays, including liquid crystal display (LCD), plasma display panel (PDP), and organic electroluminescence display (OELD).
An LCD displays an image using liquid crystal molecules. LCDs can be transmissive, reflective, or transflective (a combination of reflective and transmissive types), depending on the location of the light source. A transmissive LCD is illuminated by a backlight. This type of LCD is widely used in computer displays, mobile phones and other applications requiring high luminance levels. Reflective LCDs are illuminated by external light reflected by a diffusing reflector behind the display. Transflective LCDs can work as either transmissive or reflective LCDs, i.e., transmissively when light levels are low, using a backlight, and reflectively when external light levels are high.
Backlit and edgelit LCDs have their own light source. Examples of light sources include: light emitting diode (LED), cold cathode fluorescent lamp (CCFL), and flat fluorescent lamp (FFL). Luminous efficacy is commonly used as a metric to evaluate a light source. Luminous efficiency is a measure of the proportion of the energy supplied to a lamp that is converted into light energy. It is calculated by dividing the lamp's luminous flux, measured in lumens, by the power consumption, measured in watts.
The luminous efficacy of an LED is greater than that of a CCFL or FFL, while power consumption of an LED is lower than that of a CCFL or FFL. However, optical luminance uniformity of an LED is lower than that of the CCFL or FFL. Therefore, use of an LED as a light source causes a poor display quality of the LCD device.